Think I would start with a colour palette - two neutrals, one light one dark (eg black/ white/ navy/ beige/ grey) plus 3 or 4 colours (for me olive, burgundy, rust but could be turquoise, pink, lilac etc). Then lifestyle: how do you spend your days? Home or office or outdoors? How many smart v casual clothes do you need?
Are you a skirt/ dress person or a trouser-wearer, for preference? Do you feel comfortable in pattern, florals? Geometric? Or prefer plain colours? Your favourite trouser shape(s)? Shirts or blouses? Sweats or jumpers? Or both?
For me personally (city based, office job, WFH 2/3 days per week) it would be:
Jeans: 2 mid blue (wide leg, straight/ barrel), 1 slim dark for evenings, 1 black slouchy
Trousers: 1 wide + 1 tapered/ straight in each of my neutrals
Dresses: a couple of smart/ evening and a couple of throw-on day dresses for summer
Skirts: 1 winter + 2 summer
Jumpsuits: 1 smart evening, 1 loose linen for summer, 1 smartish for the office and 1 denim/ twill
Shirts: 1 denim, 1 casual stripe, 1 plain poplin
Blouses/ long-sleeve tops: 6 in key colours
T-shirts: 6 in mix of neutrals: colours
Knitwear: 2 sweatshirts, 2 fine-knit, 2 chunky jumpers
A great blazer (ideally a suit with one of your smart trousers)
A great denim jacket
A shacket
Another smart jacket/ blazer in a neutral
2 winter coats, 1 long 1 short
A proper waterproof coat/ jacket
A great trench
Trainers x 2
Loafers
Heels x 1
Evening flats x 1
Sandals smart and casual
In reality I have a lot more clothes than this . Need an urgent clear-out!